Benzoylphenylureas

It was further shown that such equations could be extended to a wide variety of amides and related compounds and even allowed the prediction of the degradation products of agrochemicals of the benzoylphenylurea type [13]... 

The development of class-selective antibodies is another approach to multi-analyte analysis. The analyst may design haptens that will generate antibodies that recognize an epitope common to several compounds, as explained above for the analysis of pyrethroids by measuring PBA. Other examples of class-selective immunoassays that have been developed are mercapturates," glucuronides, pyrethroids, organophosphate insecticides, and benzoylphenylurea insecticides." ... 

For an individual pesticide (e.g., carbendazim) or a limited class of pesticides (e.g., carbamates, benzoylphenylureas, pyrethroids ), it may be possible to optimize the SPE conditions so that the pesticide(s) are selectively retained on the cartridge. A wash step can be introduced to elute the matrix selectively, thus producing an extremely clean extract. For example, when cleaning up sample extracts for carbendazim analysis, a cation-exchange (SCX) cartridge may be used and the pH carefully controlled to retain the carbendazim firmly, whilst the co-extractives are washed to waste. The carbendazim residues can then be eluted from the column by adjusting the pH. 

For example, the 1,2,2 trifluoroethyl group has found use in the fungicide tetraconezole (6-1), whereas the 1,1,2,2-tetrafluoroethyl group is encountered in the benzoylphenylurea insecticide hexaflumuron (6-2), which is used to control locust and grasshoppers in Sahalian grasslands (Fig. 6.1). 

The choice between the STERIMOL and MTD approaches is dependent on some properties of the series studied, e.g. the number of members in relation to the number of substitution positions In those cases where the resulting degrees of freedom are sufficient, the STERIMOL approach gives the most satisfactory results (e.g. in the studies on the DDT analogs and to a lesser extent in benzoylphenylureas Table VII). But in opposite cases,... 

SI Wie, BD Hammock. Comparison of coating and immunizing antigen structure on the sensitivity and specificity of immunoassays for benzoylphenylurea insecticides. J Agric Food Chem 32 1294-1301, 1984. 

Sotomatsu, T., Nakagawa, N., Fujita, T. (1987) Quantitative structure-activity studies of benzoylphenylurea larvicides. IV. Benzoyl ortho substituent effects and molecular conformation. Pestic. Biochem. Physiol. 27, 156-164. 

Benzoylphenylurea insecticides are all derivatives of urea (H2NCONH2). Several benzoylphenylureas have been developed and used to control a variety of insect pests. Currently, diflubenzuron is registered for control of lepidopterous insects, mosquitoes, boll weevils, flies, and so forth. Its oral LD50 in rats is 4640 mg/kg. 

Diflubenzuron will be used to illustrate the metabolic fate of benzoylphenylurea insecticides (Figure 8.30). The major pathways involved are cleavage of the urea linkage that occurs on either side of the carbonyl. In addition, hydroxylation occurs at both phenyl rings. There is no evidence that halogens were removed from the phenyl rings. 

S.L Wie, B.D. Hammock, Comparison of Coating and Immunizing Antigen Structure on the Sensitivity and Specificity of Immunoassays for Benzoylphenylurea Insecticides , /. Agric. Food Chem., 32, 1294-1301 (1984). 

Table III. Comparative Biological Response of 4 -(1,1,2,2-Tetratluoro-2-phenyletho) y)benzoylphenylureas...

From its unique symptom and new mode of action flubendiamide would be expected not to show cross-resistance with conventional insecticides. Thus, when the activity of flubendiamide against larvae of P. xylosteUa resistant to synthetic pyrethroids, benzoylphenylureas, organophosphates and carbamates was evaluated, flubendiamide provided the same EC50 values against both the resistant and the susceptible strains [8, 13], The absence of cross-resistance between flubendiamide and conventional insecticides is probably because of its new mode of action. This indicates that flubendiamide will fit well into insecticide resistance management (IRM) programs. 

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